This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
ACK acknowledge
BTS base transceiver system
BW bandwidth
C-Plane control plane
CN core network
CQI channel quality indicator
DC dual carrier
DL downlink (eNB, Node B towards UE)
DTX discontinuous transmission
E-DCH enhanced downlink channel
EDGE enhanced data rates for GSM evolution
eNB EUTRAN Node B (evolved Node B)
EPC evolved packet core
EUTRAN evolved UTRAN (LTE)
GGSN gateway general packet radio system support node
GSM global system for mobile communication
HARQ hybrid automatic repeat request
HO handover
HS-DSCH high speed downlink shared channel
HS-SCCH high speed shared control channel
HSPA high speed packet access
HSDPA high speed downlink packet access
HSUPA high speed uplink packet access
I-HSPA internet HSPA (evolved HSPA)
IP internet protocol
L1 layer 1 (physical (Phy) layer)
L2 layer 2 (MAC layer)
LTE long term evolution
MAC medium access control
MM/MME mobility management/mobility management entity
NACK not acknowledge/negative acknowledge
NBAP Node B application part (signaling)
Node B base station (includes BTS)
OFDMA orthogonal frequency division multiple access
O&M operations and maintenance
PDCP packet data convergence protocol
PDU protocol data unit
Phy physical
PMI pre-coding matrix index
PRB physical resource block
PDCCH physical downlink control channel
PDSCH physical downlink shared channel
PUCCH physical uplink control channel
PUSCH physical uplink shared channel
RACH random access channel
RAT radio access technology
RB radio bearer
RE resource element
RLC radio link control
RNC radio network controller
ROHC robust (internet) header compression
RRC radio resource control
SAW stop-and-wait
SC-FDMA single carrier, frequency division multiple access
SGSN serving gateway support node
SGW serving gateway
SINR signal to interference plus noise ratio
SR scheduling request
TCP transmission control protocol
TFRC TCP-friendly rate control
TTI transmit time interval
U-Plane user plane
UE user equipment
UL uplink (UE towards eNB, Node B)
UTRAN universal terrestrial radio access network
WCDMA wideband code division multiple access
The specification of a communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as EUTRA) has been specified by 3GPP in Rel-8 (release eight). As specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.10.0 (2009-9), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8). This system may be referred to for convenience as LTE Rel-8 (which also contains 3G HSPA and its improvements). In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.1.0 (2009-9).
FIG. 1A reproduces FIG. 4.1 of 3GPP TS 36.300, and shows the overall architecture of the E-UTRAN system. The E-UTRAN system includes eNBs, providing the EUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (SGW) by means of a S1 interface. The S1 interface supports a many to many relationship between MMEs/Serving Gateways and eNBs.
The eNB hosts the following functions:
functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);
IP header compression and encryption of the user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards Serving Gateway;
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
measurement and measurement reporting configurations to provide mobility and scheduling.
Of particular interest herein are the further releases of 3GPP LTE targeted towards future IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A).
Reference can be made to 3GPP TR 36.814, V1.3.1 (2009-06), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Further Advancements for E-UTRA Physical Layer Aspects (Release 9). Reference can also be made to 3GPP TR 36.913, V8.0.1 (2009-03), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 8). A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost.
GSM, WCDMA, and LTE in their first releases utilized single carrier transmission. Since then, multicarrier operation has been introduced in GERAN EGDE and WCDMA HSDPA (TS25.308 Rel-8-Rel-9) and HSUPA in (TS25.319 Rel9) operation. In HSPA multicarrier operation, the UE and Node B transmit on two parallel carriers in quite an independent manner and the multicarrier operation can be seen as multiple parallel single carrier transmissions performed on different carrier frequencies to/from the single UE. The multicarrier operation in HSDPA (dual cell or dual band) supports only single carrier uplink operation, but the Dual carrier HSUPA requires dual carrier downlink operation.
As is specified in 3GPP TR 36.913, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of Rel-8 LTE, e.g., up to 100 MHz, to achieve the peak data rate of 100 mega-bits per second (Mbit/s) for high mobility and 1 Gbit/s for low mobility. LTE-A (to be included into 3GPP Release-10) is going to include carrier aggregation (CA), providing the capability to aggregate together up to five LTE carriers referred to as Component Carriers (CCs). The basic principle of CA in LTE for a single RAT is presented on FIG. 1B, which shows an example of the carrier aggregation, where M Rel-8 component carriers are combined together to form M×Rel-8 BW, e.g. 5×20 MHz=100 MHz given M=5.
Rel-8 terminals receive/transmit on one component carrier, whereas LTE-Advanced terminals may receive/transmit on multiple component carriers simultaneously (as shown in FIG. 1B) to achieve higher (e.g., wider) bandwidths. Basic scenarios for both downlink and uplink will be included into Release-10 (Rel-10). Similar work has also been carried out in the 3GPP in the context of HSDPA. In Release-10 the work on four-carrier HSDPA is currently ongoing, providing support for up to four, five mega-Hertz (MHz) carriers.
In LTE, the carrier aggregation, also called the multicarrier solution, is one of the main features to be defined for Rel-10 (TR36.814 and TR36.912) for LTE-A. In LTE also the basic principles are similar as the component carriers (single Rel-8 carrier) operate independently. Also in this specification, work will contain the operation with single carrier uplink with multiple downlink carriers.
The availability of the frequency spectrum on multiple bands is a challenge, as operators often have their bands occupied by, e.g., HSPA deployments and may be able to get new LTE spectrum only, e.g., for 2.6 GHz. Further, none of work so far has considered the carrier aggregation or multicarrier operation between different radio technologies.